Clinical illumination devices, especially those using a multi-lamp fixture, should desirably fill the following conditions:
(A) All the lamps can be equally focused on the surface to be illuminated, thereby enhancing the illuminating effect.
(B) A horizontal shift or a depth change of the lamp light focus is permitted so that the necessary part of a patient's body lying on the operating table can be well illuminated.
(C) The foci of all lamps can be shifted in a well-set condition so that their shift can be clearly traced in changing their horizontal position or depth.
(D) The illuminating fixture is not moved above the operating table so that the patient on the table can be protected from secondary infection with microbes originating from dust which naturally collects on or adheres to the lamp case and drops onto the patient's body when the lamp case is moved.
(E) The above mentioned well-set condition of the lamp foci is not disturbed even after long use.
(F) The illuminating fixture is a simple one which can be readily installed on the ceiling of an existing operating room without any major modification, that is, one with high availability of space.
(G) The illuminating fixture is so simple in construction that it can be conveniently maintained, inspected or repaired.
Of these conditions, (a) to (d) have been variously filled separately, but in no method or fixture all of the conditions (a) to (d) have been filled at the same time. To the best knowledge of the present inventor, there exists not any method or fixture that can fill all of the conditions (a) to (g).